1. Field of the Invention
This invention relates to engine diagnostics, and more particularly to determining the presence of air at the fuel intake of an internal combustion engine.
2. Description of the Prior Art
In the fuel system of internal combustion engines, a fuel pump is normally disposed in proximity to the engine, and pulls a vacuum between it and the fuel tank so as to draw fuel to the engine. If there are minor leaks in the fuel system, air can be drawn into the fuel. Although a small amount of air in the fuel does not hamper steady state engine operation, air in the fuel can accumulate at the fuel pump during periods when the engine is shut off or idling. This can cause roughness, skipping and loss of power in the engine. When the air accumulates with the engine off, hard starting may result.
Typically, the air which accumulates at the fuel intake of the engine is purged by a full power acceleration burst; thereafter only minute amounts of air being distributed in the fuel.